POSITION READING DEVICE

摘要

PROBLEM TO BE SOLVED: To completely prevent noise against a tablet and to read a position with a high accuracy by setting a position read period to convert an output signal of a tablet into position information out of a display period of a display device and fixing a level of a voltage that is applied to a display panel in a position read period. SOLUTION: A position read period generation circuit 9 supplies a position read period signal 108 of a low level to a signal fixing circuit 8 and a period notification circuit 10. A CPU 1 can recognize the start of a position read area by a position read notification signal 109 that is supplied from the circuit 10 even while the CPU 1 is carrying out another process. When the circuit 8 fixes the levels of a display data transfer signal and a horizontal scan signal in a scan period of the position read area, the horizontal scan signal never produces its level change point nor the change point of a liquid crystal alternating signal. Therefore, the noise can be completely prevented in the scan period of the position read area.